High energy radiation from the sun, such as UV and high-energy visible light, is known to be responsible for cellular damage. While most of the radiation below 280 nm in wavelength is absorbed by the earth's atmosphere, photons possessing wavelengths ranging between 280 and 400 nm have been associated with several ocular disorders including corneal degenerative changes, and age related cataract and macular degeneration. (See Statement on Ocular Ultraviolet Radiation Hazards in Sunlight, American Optometric Association, Nov. 10, 1993). The human cornea absorbs radiation up to 320 nm in wavelength (30% transmission) (Doutch, J. J., Quantock, A. J., Joyce, N. C., Meek, K. M, Biophys. J, 2012, 102, 1258-1264), but is inefficient in protecting the back of the eye from radiation ranging from 320 to 400 nm in wavelength.
Contact lens standards define the upper UV radiation wavelength at 380 nm. The current Class I UV blocking criteria defined by the American Optometric Association require >99% of the radiation between 280 and 315 nm (UV B) and >90% of the 316 to 380 nm (UV A) radiation to be absorbed by the contact lens. While the criteria effectively address protection of the cornea (<1% UV B transmittance), there is little attention paid to the lower energy UV radiation (>380<400 nm) and the high energy visible radiation associated with retinal damage (Ham, W. T, Mueller, H. A., Sliney, D. H. Nature 1976; 260(5547):153-5).
Polymerizable compounds possessing appropriate chromophores, if used as ophthalmic device monomers, can help protect the cornea, as well as the interior cells in the ocular environment, from degradation caused by high energy light.